Methods of manufacturing highly crosslinked polymer particulate

ABSTRACT

Methods of manufacturing highly crosslinked polymer particulate. The methods include positioning a granular polymeric material within a crosslinking apparatus and crosslinking the granular polymeric material with the crosslinking apparatus to form a highly crosslinked polymeric material. The methods also include forming a plurality of crosslinked polymer granules from the highly crosslinked polymeric material.

CROSS-REFERENCE TO RELATED APPLICATION

This application also claims the benefit of U.S. Provisional Application62/888,214 filed Aug. 16, 2019 entitled “Crosslinked GranularPolyethylene and U.S. Provisional Application 62/944,106 filed Dec. 5,2019 entitled “Highly Crosslinked Polymer Particulate,” the entiretiesof which are incorporated by reference herein. This application alsoclaims the benefit of U.S. Provisional Application 62/943,978 filed Dec.5, 2019 entitled “Method of Manufacturing Crosslinked PolymerParticulate” and U.S. Provisional Application 62/888,221 filed Aug. 16,2019 entitled “Method of Manufacturing Crosslinked GranularPolyethylene,” the entireties of which are incorporated by referenceherein. This application is also related to U.S. Provisional Application62/890,185 filed Aug. 22, 2019 entitled” Granular CrosslinkedPolyethylene as a Hydraulic Fracturing Proppant”, the entirety of whichis incorporated by reference herein. This application is also related toU.S. Provisional Application 62/890,186 filed Aug. 22, 2019 entitled“Granular Crosslinked Polyethylene as a Loss Circulation Material in aWellbore Operation Fluid”, the entirety of which is incorporated byreference herein. This application is also related to U.S. ProvisionalApplication 62/890,188 filed Aug. 22, 2019 entitled “GranularCrosslinked Polyethylene as a Density Modifier in a Wellbore OperationFluid Mixture”, the entirety of which is incorporated by referenceherein. This application is also related to U.S. Provisional Application62/904,993 filed Sep. 24, 2019 entitled “Granular CrosslinkedPolyethylene as a Density Modifier in a Wellbore Operation FluidMixture”, the entirety of which is incorporated by reference herein.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to methods of manufacturinghighly crosslinked polymer particulate, and more specifically to methodsof manufacturing highly crosslinked polymer particulate that includespolyethylene.

BACKGROUND OF THE DISCLOSURE

Polyethylene exhibits chemical and/or material properties that cause itto be widely utilized in industry. While suitable for many applications,polyethylene may be relatively soft, may be flexible, and/or may flowwhen subject to stress, especially at elevated temperatures. Inaddition, two polyethylene bodies, when brought into contact with oneanother under conditions of high stress and/or high temperature, mayagglomerate. This softness, flow, and/or agglomeration of conventionalpolyethylene may be undesirable for certain applications, wherematerials with a greater hardness, a lower propensity for flow, and/or adecreased potential for agglomeration may be desirable. Thus, thereexists a need for methods of manufacturing highly crosslinked polymerparticulate.

SUMMARY OF THE DISCLOSURE

Methods of manufacturing highly crosslinked polymer particulate. Themethods include positioning a granular polymeric material within acrosslinking apparatus. The granular polymeric material may include aplurality of polyethylene polymer chains. The methods also includecrosslinking the granular polymeric material with the crosslinkingapparatus to form a highly crosslinked polymeric material. The highlycrosslinked polymeric material may include a plurality of chemicalcrosslinks. The plurality of chemical crosslinks may include chemicalcrosslinks that covalently bond a given polyethylene polymer chain ofthe plurality of polyethylene polymer chains to another polyethylenepolymer chain of the plurality of polyethylene polymer chains. Themethods also include forming a plurality of crosslinked polymer granulesfrom the highly crosslinked polymeric material. A characteristicdimension of each crosslinked polymer granule of the plurality ofcrosslinked polymer granules may be at least 10 micrometers and at most5 millimeters.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart depicting examples of methods of manufacturinghighly crosslinked polymer particulate, according to the presentdisclosure.

FIG. 2 is a schematic illustration of examples of a crosslinkingapparatus in the form of an electron beam irradiation system that may beutilized during manufacture of highly crosslinked polymer particulate,according to the present disclosure.

FIG. 3 is a schematic illustration of examples of a crosslinkingapparatus in the form of an extrusion apparatus that may be utilizedduring manufacture of highly crosslinked polymer particulate, accordingto the present disclosure.

DETAILED DESCRIPTION AND BEST MODE OF THE DISCLOSURE

FIGS. 1-3 provide examples of methods 300 of manufacturing highlycrosslinked polymer particulate and/or of crosslinking apparatus 106that may be utilized during manufacture of the highly crosslinkedpolymer particulate, according to the present disclosure. Elements thatserve a similar, or at least substantially similar, purpose are labeledwith like numbers in each of FIGS. 1-3, and these elements may not bediscussed in detail herein with reference to each of FIGS. 1-3.Similarly, all elements may not be labeled in each of FIGS. 1-3, butreference numerals associated therewith may be utilized herein forconsistency. Elements, components, and/or features that are discussedherein with reference to one or more of FIGS. 1-3 may be included inand/or utilized with any of FIGS. 1-3 without departing from the scopeof the present disclosure.

In general, elements that are likely to be included in a particularembodiment are illustrated in solid lines, while elements that areoptional are illustrated in dashed lines. However, elements that areshown in solid lines may not be essential and, in some embodiments, maybe omitted without departing from the scope of the present disclosure.

Highly crosslinked polymer particulate, according to the presentdisclosure, includes a plurality of crosslinked polymer granules. Theplurality of crosslinked polymer granules each contains, or eachcrosslinked polymer granule of the plurality of crosslinked polymergranules contains, a polymeric material, which also may be referred toherein as a crosslinked polymeric material and/or as a highlycrosslinked polymeric material. The highly crosslinked polymericmaterial includes a plurality of polyethylene polymer chains and aplurality of chemical crosslinks. The plurality of chemical crosslinksincludes chemical crosslinks that covalently bond a given polyethylenepolymer chain of the plurality of polyethylene polymer chains to anotherpolyethylene polymer chain of the plurality of polyethylene polymerchains.

In some examples, the plurality of polyethylene polymer chains mayinclude a plurality of linear polyethylene polymer chains. In someexamples, each polyethylene polymer chain of the plurality ofpolyethylene polymer chains includes a plurality of methylene repeatunits and/or a plurality of ethylene repeat units covalently bonded toone another to form a plurality of carbon-carbon bonds.

In some examples, at least a subset of the plurality of polyethylenepolymer chains includes a branched polymer chain. The branched polymerchain may include at least one branch group, which may extend from apolymer backbone of the branched polymer chain. In some such examples, agiven chemical crosslink of the plurality of chemical crosslinks mayextend from the at least one branch group.

The at least one branch group, when present, may include any suitablenumber of carbon atoms and/or may have any suitable length. As examples,the at least one branch group may include at least 10, at least 25, atleast 50, at least 100, at least 500, at least 1,000, at least 5,000, atleast 10,000, at least 25,000, and/or at least 50,000 carbon atoms. Thecarbon atoms that form the at least one branch group may be arrangedlinearly, such as along a branch group backbone of the at least onebranch group. Alternatively, the carbon atoms that form the at least onebranch group may, themselves, form sub-branches. Stated another way, theat least one branch group may, itself, be branched.

In some examples, at least a subset of the plurality of polyethylenepolymer chains includes a pendant group that extends from the polymerbackbone of the subset of the plurality of polyethylene polymer chains.In some such examples, a given chemical crosslink of the plurality ofchemical crosslinks may extend from the pendant group. The pendantgroup, when present, may include any suitable number of carbon atoms. Asexamples, the pendant group may include at least 1, at least 2, at least3, at least 4, at least 5, at least 6, at least 7, at least 8, at least10, at least 15, at least 20, at most 50, at most 40, at most 30, atmost 20, at most 15, at most 12, at most 10, at most 8, and/or at most 6carbon atoms.

The pendant group may have and/or define any suitable structure,including linear structures, branched structures, cyclic structures,and/or combinations thereof. A specific example of the pendant groupincludes pendant groups that may decrease, or limit, a degree ofcrosslinking of the plurality of crosslinked polymer granules, such asvia increasing a minimum distance between adjacent polyethylene polymerchains and/or by making it difficult for the polymer backbones ofadjacent polyethylene polymer chains to closely pack. Examples of suchpendant groups include a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, a nonyl group, and/or a decyl group.

In some examples, and prior to formation of the plurality of chemicalcrosslinks, the pendant group may include a ring, a cyclic structure,and/or a double bond, which may permit and/or facilitate formation of acorresponding chemical crosslink. Examples of such pendant groupsinclude a cyclic hydrocarbon, a bridged cyclic hydrocarbon, anorbornene-derived pendant group, an ethylidene-derived pendant group,and/or a vinyl norbornene-derived pendant group.

The plurality of polyethylene polymer chains may be highly crosslinkedvia the plurality of chemical crosslinks. The plurality of polyethylenepolymer chains may have and/or define any suitable degree ofcrosslinking, or average degree of crosslinking. Examples of the averagedegree of crosslinking include at least 0.01%, at least 0.1%, at least1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, atleast 8%, at least 10%, at least 12%, at least 14%, at least 16%, atleast 18%, at least 20%, at least 25%, at least 30%, at least 35%, atleast 40%, at least 45%, and/or at least 50%. In some examples, thehighly crosslinked polymeric material within a given crosslinked polymergranule may be so highly crosslinked that the given crosslinked polymergranule may be defined by, at least substantially entirely by, or evenentirely by a single polymeric molecule.

As used herein, the phrase “degree of crosslinking” may refer to a molepercentage, or an average mole percentage, of repeat units within agiven polyethylene polymer chain that are crosslinked to anotherpolyethylene polymer chain. For example, a polyethylene polymer chainwith 100 repeat units and one crosslink would exhibit a “degree ofcrosslinking” of 1/100=1%. Similarly, a polyethylene polymer chain with100 repeat units and 10 crosslinks would exhibit a “degree ofcrosslinking” of 10/100=10%.

Each chemical crosslink may extend from any suitable portion of a givenpolyethylene polymer chain to any suitable portion of anotherpolyethylene polymer chain. For example, a chemical crosslink may extendfrom an ethylene repeat unit of a given polyethylene polymer chain to anethylene repeat unit of another polyethylene polymer chain to form acovalent bond therebetween. As another example, for examples in which atleast a subset of the plurality of polyethylene polymer chains includesa pendant group, a chemical crosslink may extend from a portion of apendant group included in a given polyethylene polymer chain to apendant group of another polyethylene polymer chain. Alternatively, thechemical crosslink may extend from a polymer backbone of a givenpolyethylene polymer chain to a pendant group of another polyethylenepolymer chain.

In some examples, the plurality of chemical crosslinks may bedistributed, evenly distributed, or even homogeneously distributedthroughout the plurality of crosslinked polymer granules. Stated anotherway, and in these examples, the plurality of chemical crosslinks may bedistributed throughout the plurality of crosslinked polymer granules.

In some examples, the plurality of chemical crosslinks may beheterogeneously distributed within each crosslinked polymer granule,such as when the plurality of chemical crosslinks is preferentiallydistributed proximate an external surface of each crosslinked polymergranule. Stated another way, each crosslinked polymer granule mayinclude an external shell that exhibits a higher degree of crosslinkingrelative to a remainder of the crosslinked polymer granule.

The plurality of crosslinked polymer granules may have and/or define anysuitable structure. As examples, the plurality of crosslinked polymergranules may include and/or be a plurality of high density polyethylenegranules and/or a plurality of crosslinked high density polyethylenegranules.

In addition, the plurality of crosslinked polymer granules may haveand/or define any suitable shape. As examples, the plurality ofcrosslinked polymer granules may include a plurality of irregularlyshaped crosslinked polymer granules, a plurality of spheroid-shapedcrosslinked polymer granules, a plurality of at least partiallyspherical crosslinked polymer granules, a plurality of sphericalcrosslinked polymer granules, a plurality of at least partiallycylindrical crosslinked polymer granules, a plurality of cylindricalcrosslinked polymer granules, and/or a plurality of rod-shapedcrosslinked polymer granules. In some examples, the plurality ofcrosslinked polymer granules may include polyethylene particles producedby a polyethylene reactor and subsequently crosslinked to form theplurality of crosslinked polymer granules.

The plurality of crosslinked polymer granules may include recycledpolyethylene. As an example, the highly crosslinked polymer particulate,or the plurality of crosslinked polymer granules that comprise thehighly crosslinked polymer particulate, may include at least a thresholdfraction of a post-consumer granular polymeric material. Examples of thethreshold fraction of the post-consumer granular polymeric materialinclude 5 weight percent, 10 weight percent, 15 weight percent, 20weight percent, 25 weight percent, 30 weight percent, 40 weight percent,50 weight percent, 60 weight percent, 70 weight percent, 80 weightpercent, 90 weight percent, 95 weight percent, 99 weight percent, and/or100 weight percent.

A characteristic dimension of each crosslinked polymer granule is withina threshold characteristic dimension range of at least 10 micrometersand at most 5 millimeters. As more specific examples, a lower limit ofthe characteristic dimension range may be at least 10 micrometers, atleast 15 micrometers, at least 20 micrometers, at least 25 micrometers,at least 30 micrometers, at least 40 micrometers, at least 50micrometers, at least 75 micrometers, at least 100 micrometers, at least125 micrometers, at least 150 micrometers, at least 200 micrometers, atleast 250 micrometers, at least 300 micrometers, at least 400micrometers, at least 500 micrometers, at least 600 micrometers, atleast 700 micrometers, at least 800 micrometers, at least 900micrometers, and/or at least 1,000 micrometers. Additionally oralternatively, an upper limit of the characteristic dimension range maybe at most 5 millimeters, at most 3.5 millimeters, at most 3millimeters, at most 2.5 millimeters, at most 2 millimeters, at most 1.5millimeters, at most 1.25 millimeters, at most 1 millimeter, at most 900micrometers, at most 800 micrometers, at most 700 micrometers, at most600 micrometers, at most 500 micrometers, at most 400 micrometers,and/or at most 300 micrometers.

Examples of the characteristic dimension include a maximum extent ofeach crosslinked polymer granule and/or a diameter of each crosslinkedpolymer granule. Additional examples of the characteristic dimensioninclude an effective diameter of each crosslinked polymer granule and/ora minimum diameter of a sphere that fully contains each crosslinkedpolymer granule.

FIG. 1 is a flowchart depicting examples of methods 300 of manufacturinghighly crosslinked polymer particulate, according to the presentdisclosure. Methods 300 may include generating a granular polymericmaterial at 310 and include positioning the granular polymeric materialat 320. Methods 300 also include crosslinking the granular polymericmaterial at 330 and forming crosslinked polymer granules at 340.

In general, methods 300 describe mechanisms via which the granularpolymeric material may be converted to, or utilized to form, crosslinkedpolymer granules that form and/or define the highly crosslinked polymerparticulate. Examples of the highly crosslinked polymer particulate thatmay be manufactured utilizing methods 300 are disclosed herein. Examplesof properties of the highly crosslinked polymer particulate also aredisclosed herein.

The granular polymeric material that is utilized to form and/or definethe highly crosslinked polymer particulate may include any suitablegranular material that includes polyethylene, that includes a pluralityof polyethylene polymer chains, and/or that is not, or that does notinclude, the crosslinked polymer granules. In some examples, thegranular polymeric material may include and/or be a post-consumergranular polymeric material and/or a recycle stream of the granularpolymeric material. In these examples, the granular polymeric materialmay include at least a threshold fraction of the post-consumer granularpolymeric material. Examples of the threshold fraction of thepost-consumer granular polymeric material are disclosed herein.

In some examples, and in addition to polyethylene, the granularpolymeric material may include one or more additional materials.Examples of the one or more additional materials include anotherpolymer, a colorant, a filler, an adhesive, a metal, glass, alumina,and/or a silicate. In some such examples, the one or more additionalmaterials purposefully may be added to and/or combined with thepolyethylene to generate the granular polymeric material. In some suchexamples, such as when the granular polymeric material includes thepost-consumer granular polymeric material, the one or more additionalmaterials already may be incorporated with the polyethylene in thegranular polymeric material.

Generating the granular polymeric material at 310 may include generatingthe granular polymeric material in any suitable manner. As an example,the generating at 310 may include severing a bulk polymeric material toproduce and/or generate the granular polymeric material. Examples of thesevering include cutting, grinding, chopping, splitting, breaking,slicing, and/or otherwise decreasing a size, or a maximum dimension, ofthe bulk polymeric material to produce and/or generate the granularpolymeric material. Examples of the bulk polymeric material include apost-consumer bulk polymeric material, a polymeric film, a polymericsheet, a polymeric block, an uncrosslinked polymeric granule, and/or apolymeric fiber. Examples of the polymeric fiber include polymericcylinders, polymeric rods, polymeric filaments, and/or polymericstrings.

As another example, the granular polymeric material may includepolyethylene pellets, which may be generated within and/or by apolyethylene reactor. In these examples, the generating at 310 mayinclude generating the polyethylene pellets within the polyethylenereactor. Also in these examples, the generating at 310 may includeselecting at least one property of a catalyst, which is utilized withinthe polyethylene reactor, such that a characteristic dimension of thegranular polymeric material is within a threshold characteristicdimension range. Examples of the threshold characteristic dimensionrange are disclosed herein with respect to the threshold characteristicdimension range of the crosslinked polymer granules. Stated another way,and in some examples, a characteristic dimension of the crosslinkedpolymer granules may be at least partially defined by, or even may beequal to, the characteristic dimension of the granular polymericmaterial.

Positioning the granular polymeric material at 320 may includepositioning the granular polymeric material within a crosslinkingapparatus. This may include positioning within a hopper and/or within agranule holder of the crosslinking apparatus and/or may includepositioning to permit and/or to facilitate the crosslinking at 330. Asdiscussed, the granular polymeric material includes polyethylene and/orincludes a plurality of polyethylene polymer chains. Examples of thecrosslinking apparatus are disclosed herein.

Crosslinking the granular polymeric material at 330 may includecrosslinking the granular polymeric material with, within, and/orutilizing the crosslinking apparatus. This may include crosslinking toform a highly crosslinked polymeric material that includes a pluralityof chemical crosslinks. As discussed herein, the plurality of chemicalcrosslinks may include chemical crosslinks that covalently bond a givenpolyethylene polymer chain to another polyethylene polymer chain.

In some examples, the crosslinking at 330 may include directlycrosslinking the granular polymeric material. Stated another way,methods 300 may include maintaining a morphology, or a shape, of thegranular polymeric material during the crosslinking at 330 and/ormaintaining the morphology of the granular polymeric material in and/orwithin the highly crosslinked polymeric material and/or in and/or withinthe plurality of crosslinked polymer granules. Stated yet another way, amorphology of the granular polymeric material may be similar to, atleast substantially identical to, or even identical to the morphology ofthe granular polymeric material.

In some examples, the crosslinking at 330 may include changing themorphology of the granular polymeric material to produce and/or generatethe highly crosslinked polymeric material and/or the plurality ofcrosslinked polymer granules. As an example, the crosslinking at 330 mayinclude combining a plurality of polymeric granules of the granularpolymeric material to produce, to generate, and/or to form the highlycrosslinked polymeric material.

Forming crosslinked polymer granules at 340 may include forming aplurality of crosslinked polymer granules from and/or with the highlycrosslinked polymeric material. A characteristic dimension of eachcrosslinked polymer granule of the plurality of crosslinked polymergranules may be within a threshold characteristic dimension range,examples of which are disclosed herein.

In some examples, such as when the crosslinking at 330 includesmaintaining the morphology of the granular polymeric material, thecharacteristic dimension of each crosslinked polymer granule may bedefined, specified, and/or regulated by the characteristic dimension ofthe granular polymeric material. In some such examples, the forming at340 may be, or may be referred to herein as being, at least partiallyconcurrent with the crosslinking at 330 and/or responsive to thecrosslinking at 330.

In some examples, such as when the crosslinking at 330 includes changingthe morphology of the granular polymeric material to form the highlycrosslinked polymeric material, the characteristic dimension of the eachcrosslinked polymer granule may differ from a characteristic dimensionof the highly crosslinked polymeric material. In some such examples,forming at 340 may be, or may be referred to herein as being, at leastpartially concurrent with the crosslinking at 330 and/or responsive tothe crosslinking at 330. In some such examples, the forming at 340 maybe, or may be referred to herein as being, subsequent to thecrosslinking at 330. In some such examples, the forming at 340 furthermay include severing the highly crosslinked polymeric material to form,define, and/or produce the plurality of crosslinked polymer granules.

As discussed, the positioning at 320 may include positioning thegranular polymeric material in and/or within the crosslinking apparatusand/or the crosslinking at 330 may include crosslinking the granularpolymeric material in and/or within the crosslinking apparatus. Anexample of the crosslinking apparatus includes an electron beamirradiation system. FIG. 2 is a schematic illustration of examples of acrosslinking apparatus 106, in the form of an electron beam irradiationsystem 110, that may be utilized during manufacture of highlycrosslinked polymer particulate, according to the present disclosure.

In some examples, the crosslinking at 330 may include irradiating thegranular polymeric material with an electron beam to produce and/orfacilitate formation of the plurality of crosslinked polymer granules.As an example, and when the crosslinking apparatus includes electronbeam irradiation system 110 of FIG. 2, the crosslinking at 330 mayinclude irradiating the granular polymeric material with an electronbeam 124. In the example of FIG. 2, electron beam 124 is irradiatinggranular polymeric material 190 to form and/or define crosslinkedpolymer granules 198. Also in the example of FIG. 2, granular polymericmaterial 190 and/or crosslinked polymer granules 198 are containedwithin a granule holder 115.

The crosslinking apparatus may include an electron beam source, such aselectron beam source 120 of FIG. 2. The electron beam source may beconfigured to generate the electron beam, and the irradiating mayinclude irradiating with the electron beam and/or with, via, and/orutilizing the electron beam source.

The electron beam source may include a filament, such as filament 122 ofFIG. 2. The filament may be configured to emit the electron beam. Underthese conditions, the irradiating further may include applying anacceleration voltage to the filament to produce and/or to generate theelectron beam. The acceleration voltage may be supplied by a powersupply, such as power supply 126 of FIG. 2. Examples of the power supplyinclude a high voltage power supply, a variable voltage power supply, analternating current power supply, and/or a direct current power supply.

The acceleration voltage may be selected to produce and/or to generateat least one desired mechanical property in the crosslinked polymergranules. Examples of the at least one desired mechanical property aredisclosed herein. Additionally or alternatively, the accelerationvoltage may be selected such that the electron beam penetrates, or fullypenetrates, the granular polymeric material. Examples of theacceleration voltage include acceleration voltages of at least 200kilo-electron volts (keV), at least 400 keV, at least 600 keV, at least800 keV, at least 1 mega-electron volt (MeV) at least 2 MeV, at least 4MeV, at least 6 MeV, at least 8 MeV, at least 10 MeV, at most 20 MeV, atmost 18 MeV, at most 16 MeV, at most 14 MeV, at most 12 MeV, at most 10MeV, at most 8 MeV, at most 6 MeV, at most 4 MeV, at most 2 MeV, and/orat most 1 MeV.

The electron beam irradiation system may include a focus lens, such asfocus lens 128 of FIG. 2. An example of the focus lens includes a focuscoil configured to generate an electric field and/or a magnetic fieldthat interacts with and/or focuses the electron beam. The focus lens maybe configured to focus the electron beam, such as on the granularpolymeric material, and the irradiating may include focusing theelectron beam on the granular polymeric material with, via, and/orutilizing the focus lens.

The electron beam irradiation system may include a vacuum chamber, suchas vacuum chamber 130 of FIG. 2. When the electron beam irradiationsystem includes the vacuum chamber, the positioning at 320 may includepositioning the granular polymeric material within the vacuum chamber,such as within granule holder 115 that may be positioned within thevacuum chamber. Also when the electron beam radiation system includesthe vacuum chamber, and prior to the crosslinking at 330, methods 300also may include evacuating the vacuum chamber. The evacuating mayinclude evacuating with, via, and/or utilizing a vacuum pump, such asvacuum pump 132 of FIG. 2. Examples of the vacuum pump include a gastransfer pump, a kinetic transfer pump, a positive displacement pump,and/or an entrapment pump.

Methods 300 also may include agitating the granular polymeric materialduring the irradiating. As an example, the electron beam irradiationsystem may include an agitation apparatus, such as agitation apparatus140 of FIG. 2. Examples of the agitation apparatus include a rotatingblade, a rotating screen, and/or a vibratory agitation apparatus. Whenthe electron beam irradiation system includes the agitation apparatus,the agitating may include agitating with, via, and/or utilizing theagitation apparatus. The agitating may increase and/or improve thecrosslinking at 330. As an example, the agitating may increase apotential for complete exposure of the granular polymeric material tothe electron beam, may increase a potential for exposure of all sides ofthe granular polymeric material to the electron beam, may increase anoverall degree of crosslinking of the granular polymeric material,and/or may provide deeper penetration, on average, of the electron beaminto individual granules of the granular polymeric material.

In some examples, the irradiating may include sequentially irradiatingthe granular polymeric material utilizing a plurality of irradiationsteps. In these examples, the agitating may include agitating thegranular polymeric material between at least two irradiation stepsand/or even between each sequential pair of irradiation steps.

In some examples, and as illustrated in solid lines in FIG. 2, electronbeam irradiation system 110 may include a single electron beam source120. In such examples, the sequentially irradiating may include turningthe single electron beam source 120 on and off a plurality of times,such as to permit the agitating to be performed between the irradiationsteps and/or to permit granular polymeric material 190 and/orcrosslinked polymer granules 198 to cool between successive irradiationsteps.

In some examples, and as illustrated in solid and in dashed lines inFIG. 2, electron beam irradiation system 110 may include a plurality ofelectron beam sources 120 that may be configured to concurrently and/orsequentially irradiate granular polymeric material 190 and/orcrosslinked polymer granules 198. As an example, and as illustrated onthe left side of FIG. 2, a first electron beam source 120 may irradiategranular polymeric material 190 and/or crosslinked polymer granules 198from a top side thereof, and a second electron beam source 120 mayirradiate granular polymeric material 190 and/or crosslinked polymergranules 198 from a bottom side thereof.

As another example, electron beam irradiation system 110 may include aconveyance apparatus 178. Conveyance apparatus 178, when present, may beconfigured to operatively translate granule holder 115 such thatelectron beams 124 from different electron beam sources 120 mayirradiate granular polymeric material 190 and/or crosslinked polymergranules 198 during different time periods. In these examples, thesequentially irradiating may be performed by electron beams generated bydifferent electron beam sources.

Methods 300 may include cooling the granular polymeric material duringthe irradiating. When the irradiating includes irradiating via theplurality of irradiation steps, the cooling may include passivelycooling the granular polymeric material between successive irradiationsteps. Additionally or alternatively, the cooling also may includeactively cooling the granular polymeric material. The actively coolingmay be performed during the irradiating, subsequent to the irradiating,during the plurality of irradiation steps, and/or between successiveirradiation steps. As an example, the cooling may include contacting thegranular polymeric material with a cooling fluid stream, such as coolingfluid stream 176 of FIG. 2, which may be provided by a cooling fluidsource, such as cooling fluid source 174 of FIG. 2.

It is within the scope of the present disclosure that the irradiating,when performed, may include irradiating with any suitable beam dosage.As an example, the beam dosage may be selected to generate at least onedesired mechanical property in the crosslinked polymer granules,examples of which are disclosed herein. As more specific examples, thebeam dosage may include beam dosages of at least 1 megarads (Mrad), atleast 5 Mrad, at least 10 Mrad, at least 15 Mrad, at least 20 Mrad, atleast 30 Mrad, at least 40 Mrad, at least 60 Mrad, at least 80 Mrad, atleast 100 Mrad, at least 150 Mrad, at least 200 Mrad, at least 300 Mrad,at least 400 Mrad, at least 500 Mrad, at least 750 Mrad, at least 10³Mrad, at least 10⁴ Mrad, at least 10⁵ Mrad, at most 10⁶ Mrad, at most10⁵ Mrad, at most 10⁴ Mrad, at most 10³ Mrad, at most 750 Mrad, at most500 Mrad, at most 400 Mrad, at most 300 Mrad, at most 250 Mrad, at most200 Mrad, at most 150 Mrad, and/or at most 100 Mrad.

Another example of the crosslinking apparatus includes an extrusionapparatus. FIG. 3 is a schematic illustration of examples of acrosslinking apparatus 106 in the form of an extrusion apparatus 160that may be utilized during manufacture of highly crosslinked polymerparticulate, according to the present disclosure.

In some examples, the crosslinking at 330 may include combining thegranular polymeric material with a crosslinking agent to form amaterial-agent mixture. In these examples, the crosslinking at 330further may include extruding the material-agent mixture with theextrusion apparatus to at least partially form the plurality ofcrosslinked polymer granules.

The combining may include combining any suitable granular polymericmaterial, examples of which are disclosed herein, with any suitablecrosslinking agent. Examples of the crosslinking agent include aperoxide, an organic peroxide, di-(2,4-dichlorobenzoyl) peroxide,tert-butyl peroxybenzoate,1,1-di-(tert-butylperoxy)-3,3,5-trimethylecyclohexane, dicumyl peroxide,tert-butyl cumyl peroxide, di-tert-butyl peroxide,2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-di(2-tert-butylperoxyisopropyl)-benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, asilane, and/or an azo compound.

The combining may include combining the granular polymeric material andthe crosslinking agent in any suitable relative proportion. As examples,the combining may include combining such that the material-agent mixtureincludes at least 0.1 weight percent (wt %) of the crosslinking agent,at least 0.25 wt % of the crosslinking agent, at least 0.5 wt % of thecrosslinking agent, at least 1 wt % of the crosslinking agent, at least2 wt % of the crosslinking agent, at least 3 wt % of the crosslinkingagent, at least 4 wt % of the crosslinking agent, at least 5 wt % of thecrosslinking agent, at most 10 wt % of the crosslinking agent, at most 8wt % of the crosslinking agent, at most 6 wt % of the crosslinkingagent, at most 4 wt % of the crosslinking agent, at most 2 wt % of thecrosslinking agent, and/or at most 1 wt % of the crosslinking agent.

As illustrated in FIG. 3, the combining may include combining a granularpolymeric material 190 and a crosslinking agent 192 within a mixer 150to produce and/or generate a material-agent mixture 193. Thematerial-agent mixture then may be provided to extrusion apparatus 160,and/or to a hopper 162 of the extrusion apparatus, before beingextruded, by the extrusion apparatus, to produce and/or generate aplurality of crosslinked polymer granules 198 and/or an extruded highlycrosslinked polymeric material 196 that may be utilized to define theplurality of crosslinked polymer granules.

The extruding may include heating the material-agent mixture to generatea heated material-agent mixture and subsequently cooling the heatedmaterial-agent mixture to at least partially form the plurality ofcrosslinked polymer granules. As illustrated in FIG. 3, the extrudingmay include flowing material-agent mixture 193 through apressure-generating apparatus 164, such as a screw extruder, that may beconfigured to apply a mechanical force and/or a pressure to thematerial-agent mixture. The heating may include heating with, via,and/or utilizing a heater 166 to produce and/or generate a heatedmaterial-agent mixture 194. A combination of the heat, pressuregenerated within the pressure-generating apparatus, and contact betweenthe granular polymeric material and the crosslinking agent may cause thegranular polymeric material to crosslink, within the extrusionapparatus, to form the extruded highly crosslinked polymeric materialand/or to at least partially define the crosslinked polymer granules.The heating may include heating to any suitable temperature. Asexamples, the heating may include heating the material-agent mixturewithout melting the granular polymeric material and/or heating to atemperature of at least 10 degrees Celsius (° C.), at least 12° C., atleast 14° C., at least 16° C., at least 18° C., at most 30° C., at most28° C., at most 26° C., at most 24° C., at most 22° C., and/or at most20° C.

In some examples, the extruding may include extruding such that theextrusion structure forms, or directly forms, the plurality ofcrosslinked polymer granules. In other examples, the extruding mayinclude extruding to form the extruded highly crosslinked polymericmaterial, which may be larger than a desired size, or maximum extent, ofthe plurality of crosslinked polymer granules. In these examples, theforming at 340 further may include severing the extruded highlycrosslinked polymeric material to form the plurality of crosslinkedpolymer granules. Examples of the severing include cutting, grinding,chopping, breaking, slicing, splitting, and/or otherwise decreasing asize, or a maximum dimension, of the extruded highly crosslinkedpolymeric material to produce and/or generate the crosslinked polymergranules.

As illustrated in FIG. 3, the extrusion structure may include anextrusion die 168 that may define at least one aperture, and theextruded highly crosslinked polymeric material may be produced from theaperture. As also illustrated in FIG. 3, extruded highly crosslinkedpolymeric material 196 may be provided to a severing apparatus 170,which may sever the extruded highly crosslinked polymeric material toproduce and/or generate the plurality of crosslinked polymer granules198. Examples of severing apparatus 170 include a cutter, a grinder, achopper, a splitter, and/or a slicer.

In the examples illustrated in FIGS. 2-3, crosslinking apparatus 106 hasbeen illustrated and described as either electron beam irradiationsystem 110 or extrusion apparatus 160. However, it is within the scopeof the present disclosure that other crosslinking apparatus may beutilized to perform methods 300. Additionally or alternatively, it isalso within the scope of the present disclosure that extrusion apparatus160 and electron beam irradiation system 110 may be utilized in series.As an example, and as discussed herein, extrusion apparatus 160 may beutilized to produce and/or generate crosslinked polymer granules 198.Subsequently, electron beam irradiation system 110 may be utilized toirradiate the crosslinked polymer granules to cause additionalcrosslinking within the crosslinked polymer granules and/or to increasethe degree of crosslinking of the crosslinked polymer granules.

As used herein, the phrase “highly crosslinked” may be utilized tomodify and/or to describe polymeric material, polymer granules that areat least partially formed from the polymeric material, and/or polymerparticulate that includes the polymer granules. Such polymeric material,polymer granules, and/or polymer particulate, when “highly crosslinked,”include polyethylene polymer chains with a degree of crosslinkingsufficient to provide the highly crosslinked polymeric material, thehighly crosslinked polymer granules, and/or the highly crosslinkedpolymer particulate with one or more of the below-described properties.Stated another way, a degree of crosslinking needed to provide thepolymeric material, the polymer granules, and/or the polymer particulatewith one or more of the below-described properties indicates that thepolymeric material is a highly crosslinked polymeric material, that thepolymer granules are highly crosslinked polymer granules, and/or thepolymer particulate is a highly crosslinked polymer particulate in thecontext of the instant disclosure.

As an example, and upon fluid contact with naturally occurring liquidhydrocarbons, such as crude oil, within a hydrocarbon well, the highlycrosslinked polymer particulate disclosed herein may undergo less than athreshold increase in mass due to absorption of the naturally occurringliquid hydrocarbons. Examples of the threshold increase in mass includethreshold increases of 0.05%, 0.1%, 0.25%, 0.5%, 0.75%, 1%, 2%, 3%, 4%,and/or 5%.

As another example, and upon fluid contact with crude oil for a timeperiod of 8 weeks, at a temperature of 85 degrees Celsius, and under auniaxial stress of 35 Megapascals, the highly crosslinked polymerparticulate disclosed herein undergoes at most a threshold increase instrain.

Examples of the threshold increase in strain include increases of 1%,2%, 3%, 4%, 5%, 6%, 8%, and/or 10%.

As yet another example, and when subjected to a confining stress of 42Megapascals at a temperature of 85 degrees Celsius, a monolayer of thehighly crosslinked polymer particulate disclosed herein defines at leasta threshold fluid conductivity. Examples of the threshold fluidconductivity include fluid conductivities of 0.5×10⁴ micrometers³, 1×10⁴micrometers³, 1.5×10⁴ micrometers³, 1.75×10⁴ micrometers³, 2×10⁴micrometers³, 2.25×10⁴ micrometers³, 2.75×10⁴ micrometers³, 3×10⁴micrometers³, 3.5×10⁴ micrometers³, 4×10⁴ micrometers³, 4.5×10⁴micrometers³, 5×10⁴ micrometers³, and/or 6×10⁴ micrometers³.

As another example, the highly crosslinked polymer particulate disclosedherein may have at least a threshold onset of melting temperature.Examples of the threshold onset of melting temperature includetemperatures of 40 degrees Celsius, 45 degrees Celsius, 50 degreesCelsius, 55 degrees Celsius, 60 degrees Celsius, 65 degrees Celsius, 70degrees Celsius, 75 degrees Celsius, 80 degrees Celsius, 85 degreesCelsius, 90 degrees Celsius, 95 degrees Celsius, 100 degrees Celsius,105 degrees Celsius, and/or 110 degrees Celsius.

As yet another example, the highly crosslinked polymer particulatedisclosed herein may have at least a threshold melting temperature.Examples of the threshold melting temperature include temperatures of 60degrees Celsius, 65 degrees Celsius, 70 degrees Celsius, 75 degreesCelsius, 80 degrees Celsius, 85 degrees Celsius, 90 degrees Celsius, 95degrees Celsius, 100 degrees Celsius, 105 degrees Celsius, 110 degreesCelsius, 115 degrees Celsius, 120 degrees Celsius, 125 degrees Celsius,130 degrees Celsius, and/or 135 degrees Celsius.

As another example, the highly crosslinked polymer particulate disclosedherein may exhibit less than a threshold strain when subject to a stressof 35 Megapascals at a temperature of 85 degrees Celsius. Examples ofthe threshold strain include threshold strains of 40%, 39%, 38%, 37%,36%, 35%, 34%, 33%, 32%, 31%, and/or 30%.

As yet another example, and when compared to an analogous uncrosslinkedpolymer particulate, the highly crosslinked polymer particulatedisclosed herein may exhibit at least a threshold decrease in strainwhen subject to a stress of 35 Megapascals at a temperature of 85degrees Celsius. Examples of the threshold decrease in strain includedecreases of 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, and/or 2%.

As used herein, the phrase “analogous uncrosslinked polymerparticulate,” when utilized to compare to the highly crosslinked polymerparticulate disclosed herein, may include an uncrosslinked polymerparticulate that has and/or defines an identical chemical structure tothat of the highly crosslinked polymer particulate with the exceptionthat the uncrosslinked polymer particulate does not include theplurality of chemical crosslinks. Stated another way, a granularpolymeric material may be crosslinked to form and/or define the highlycrosslinked polymer particulate, and the analogous uncrosslinked polymerparticulate may refer to the granular polymeric material prior to beingcrosslinked to form the highly crosslinked polymer particulate.

The highly crosslinked polymeric material, the highly crosslinkedpolymer granules, and/or the highly crosslinked polymer particulatedisclosed herein may, in addition to one or more of the above-describedproperties, also, or optionally also, exhibit one or more of thebelow-described properties. As an example, the highly crosslinkedpolymer particulate may define a particulate density. Examples of theparticulate density include densities of at least 0.8 grams per cubiccentimeter (g/cc), at least 0.82 g/cc, at least 0.84 g/cc, at least 0.86g/cc, at least 0.88 g/cc, at least 0.9 g/cc, at least 0.92 g/cc, atleast 0.94 g/cc, at least 0.96 g/cc, at least 0.98 g/cc, at least 1g/cc, at most 2.6 g/cc, at most 2.4 g/cc, at most 2.2 g/cc, at most 2g/cc, at most 1.8 g/cc, at most 1.6 g/cc, at most 1.4 g/cc, at most 1.2g/cc, at most 1.1 g/cc, at most 1 g/cc, at most 0.99 g/cc, at most 0.98g/cc, at most 0.97 g/cc, and/or at most 0.96 g/cc.

As another example, and when compared to the analogous uncrosslinkedpolymer particulate, the highly crosslinked polymer particulate mayresist fusing of the plurality of crosslinked polymer granules whenexposed to a compressive force. Stated another way, fusing of the highlycrosslinked polymer particulate may be quantitatively less than fusingof the analogous uncrosslinked polymer particulate. As examples, fusingof the highly crosslinked polymer particulate may be at least 10% less,at least 20% less, at least 30% less, at least 40% less, at least 50%less, at least 60% less, at least 70% less, at least 80% less, and/or atleast 90% less than fusing of the analogous uncrosslinked polymerparticulate when exposed to the compressive force.

As yet another example, and when compared to the analogous uncrosslinkedpolymer particulate, the highly crosslinked polymer particulate mayresist flowing of the plurality of crosslinked polymer granules whenexposed to the compressive force. Stated another way, the flow of thehighly crosslinked polymer particulate may be quantitatively less thanthe flow of the analogous uncrosslinked polymer particulate. Asexamples, flow of the highly crosslinked polymer particulate may be atleast 10% less, at least 20% less, at least 30% less, at least 40% less,at least 50% less, at least 60% less, at least 70% less, at least 80%less, and/or at least 90% less than the flow of the analogousuncrosslinked polymer particulate when exposed to the compressive force.

As another example, and when compared to the analogous uncrosslinkedpolymer particulate, the highly crosslinked polymer particulate maymaintain fluid permeability among and/or between the plurality ofcrosslinked polymer granules when exposed to the compressive force.Stated another way, the fluid permeability of the highly crosslinkedpolymer particulate may decrease to a lesser extent when compared tofluid permeability of the analogous uncrosslinked polymer particulate.As examples, fluid permeability of the highly crosslinked polymerparticulate may decrease at least 10% less, at least 20% less, at least30% less, at least 40% less, at least 50% less, at least 60% less, atleast 70% less, at least 80% less, and/or at least 90% less than thefluid permeability of the analogous uncrosslinked polymer particulatewhen exposed to the compressive force.

In the present disclosure, several of the illustrative, non-exclusiveexamples have been discussed and/or presented in the context of flowdiagrams, or flow charts, in which the methods are shown and describedas a series of blocks, or steps. Unless specifically set forth in theaccompanying description, it is within the scope of the presentdisclosure that the order of the blocks may vary from the illustratedorder in the flow diagram, including with two or more of the blocks (orsteps) occurring in a different order and/or concurrently.

As used herein, the term “and/or” placed between a first entity and asecond entity means one of (1) the first entity, (2) the second entity,and (3) the first entity and the second entity. Multiple entities listedwith “and/or” should be construed in the same manner, i.e., “one ormore” of the entities so conjoined. Other entities may optionally bepresent other than the entities specifically identified by the “and/or”clause, whether related or unrelated to those entities specificallyidentified. Thus, as a non-limiting example, a reference to “A and/orB,” when used in conjunction with open-ended language such as“comprising” may refer, in one embodiment, to A only (optionallyincluding entities other than B); in another embodiment, to B only(optionally including entities other than A); in yet another embodiment,to both A and B (optionally including other entities). These entitiesmay refer to elements, actions, structures, steps, operations, values,and the like.

As used herein, the phrase “at least one,” in reference to a list of oneor more entities should be understood to mean at least one entityselected from any one or more of the entities in the list of entities,but not necessarily including at least one of each and every entityspecifically listed within the list of entities and not excluding anycombinations of entities in the list of entities. This definition alsoallows that entities may optionally be present other than the entitiesspecifically identified within the list of entities to which the phrase“at least one” refers, whether related or unrelated to those entitiesspecifically identified. Thus, as a non-limiting example, “at least oneof A and B” (or, equivalently, “at least one of A or B,” or,equivalently “at least one of A and/or B”) may refer, in one embodiment,to at least one, optionally including more than one, A, with no Bpresent (and optionally including entities other than B); in anotherembodiment, to at least one, optionally including more than one, B, withno A present (and optionally including entities other than A); in yetanother embodiment, to at least one, optionally including more than one,A, and at least one, optionally including more than one, B (andoptionally including other entities). In other words, the phrases “atleast one,” “one or more,” and “and/or” are open-ended expressions thatare both conjunctive and disjunctive in operation. For example, each ofthe expressions “at least one of A, B, and C,” “at least one of A, B, orC,” “one or more of A, B, and C,” “one or more of A, B, or C,” and “A,B, and/or C” may mean A alone, B alone, C alone, A and B together, A andC together, B and C together, A, B, and C together, and optionally anyof the above in combination with at least one other entity.

In the event that any patents, patent applications, or other referencesare incorporated by reference herein and (1) define a term in a mannerthat is inconsistent with and/or (2) are otherwise inconsistent with,either the non-incorporated portion of the present disclosure or any ofthe other incorporated references, the non-incorporated portion of thepresent disclosure shall control, and the term or incorporateddisclosure therein shall only control with respect to the reference inwhich the term is defined and/or the incorporated disclosure was presentoriginally.

As used herein the terms “adapted” and “configured” mean that theelement, component, or other subject matter is designed and/or intendedto perform a given function. Thus, the use of the terms “adapted” and“configured” should not be construed to mean that a given element,component, or other subject matter is simply “capable of” performing agiven function but that the element, component, and/or other subjectmatter is specifically selected, created, implemented, utilized,programmed, and/or designed for the purpose of performing the function.It is also within the scope of the present disclosure that elements,components, and/or other recited subject matter that is recited as beingadapted to perform a particular function may additionally oralternatively be described as being configured to perform that function,and vice versa.

As used herein, the phrase, “for example,” the phrase, “as an example,”and/or simply the term “example,” when used with reference to one ormore components, features, details, structures, embodiments, and/ormethods according to the present disclosure, are intended to convey thatthe described component, feature, detail, structure, embodiment, and/ormethod is an illustrative, non-exclusive example of components,features, details, structures, embodiments, and/or methods according tothe present disclosure. Thus, the described component, feature, detail,structure, embodiment, and/or method is not intended to be limiting,required, or exclusive/exhaustive; and other components, features,details, structures, embodiments, and/or methods, including structurallyand/or functionally similar and/or equivalent components, features,details, structures, embodiments, and/or methods, are also within thescope of the present disclosure.

As used herein, “at least substantially,” when modifying a degree orrelationship, may include not only the recited “substantial” degree orrelationship, but also the full extent of the recited degree orrelationship. A substantial amount of a recited degree or relationshipmay include at least 75% of the recited degree or relationship. Forexample, an object that is at least substantially formed from a materialincludes objects for which at least 75% of the objects are formed fromthe material and also includes objects that are completely formed fromthe material. As another example, a first length that is at leastsubstantially as long as a second length includes first lengths that arewithin 75% of the second length and also includes first lengths that areas long as the second length.

INDUSTRIAL APPLICABILITY

The systems and methods disclosed herein are applicable to industriesthat utilize polyethylene.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and subcombinations of the various elements, features,functions, and/or properties disclosed herein. Similarly, where theclaims recite “a” or “a first” element or the equivalent thereof, suchclaims should be understood to include incorporation of one or more suchelements, neither requiring nor excluding two or more such elements.

It is believed that the following claims particularly point out certaincombinations and subcombinations that are directed to one of thedisclosed inventions and are novel and non-obvious. Inventions embodiedin other combinations and subcombinations of features, functions,elements, and/or properties may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such amended or new claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower, or equal in scope to the original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

The invention claimed is:
 1. A method of manufacturing a crosslinkedpolymer particulate, the method comprising: positioning a granularpolymeric material within a crosslinking apparatus, wherein the granularpolymeric material includes a plurality of polyethylene polymer chains;crosslinking the granular polymeric material with the crosslinkingapparatus to form a crosslinked polymeric material that includes aplurality of chemical crosslinks, wherein the plurality of chemicalcrosslinks includes chemical crosslinks that covalently bond a givenpolyethylene polymer chain of the plurality of polyethylene polymerchains to another polyethylene polymer chain of the plurality ofpolyethylene polymer chains; and forming a plurality of crosslinkedpolymer granules from the crosslinked polymeric material, wherein acharacteristic dimension of each crosslinked polymer granule of theplurality of crosslinked polymer granules is at least 10 micrometers andat most 5 millimeters, and wherein the crosslinked polymeric materialhas a particulate density of 1 g/cc to 2.6 g/cc.
 2. The method of claim1, wherein the forming the plurality of crosslinked polymer granules isat least one of: (i) at least partially concurrent with thecrosslinking; (ii) responsive to the crosslinking; and (iii) subsequentto the crosslinking.
 3. The method of claim 1, wherein the crosslinkingincludes at least one of: (i) directly crosslinking the granularpolymeric material; and (ii) maintaining a morphology of the granularpolymeric material in the plurality of crosslinked polymer granules. 4.The method of claim 1, wherein the forming the plurality of crosslinkedpolymer granules includes at least one of: (i) changing a morphology ofthe granular polymeric material to form the plurality of crosslinkedpolymer granules; and (ii) combining a plurality of polymeric granulesof the granular polymeric material to form the crosslinked polymericmaterial.
 5. The method of claim 1, wherein the forming the plurality ofcrosslinked polymer granules includes severing the crosslinked polymericmaterial to form the plurality of crosslinked polymer granules.
 6. Themethod of claim 1, wherein the crosslinking includes irradiating thegranular polymeric material with an electron beam to facilitate theforming the plurality of crosslinked polymer granules.
 7. The method ofclaim 6, wherein the crosslinking apparatus includes an electron beamsource configured to generate the electron beam, and further wherein theirradiating includes irradiating via the electron beam source.
 8. Themethod of claim 7, wherein the electron beam source includes a filamentconfigured to emit the electron beam, wherein the irradiating includesapplying an acceleration voltage to the filament to generate theelectron beam, and further wherein at least one of: (i) the accelerationvoltage is at least 200 kilo-electron volts; (ii) the accelerationvoltage is selected to generate at least one desired mechanical propertyin the crosslinked polymer granules; and (iii) the acceleration voltageis selected such that the electron beam fully penetrates the granularpolymeric material.
 9. The method of claim 7, wherein the crosslinkingapparatus includes a vacuum chamber, wherein the positioning includespositioning the granular polymeric material within the vacuum chamber,and further wherein, prior to the crosslinking, the method includesevacuating the vacuum chamber.
 10. The method of claim 7, wherein themethod further includes agitating the granular polymeric material duringthe irradiating.
 11. The method of claim 7, wherein the irradiatingincludes sequentially irradiating the granular polymeric material with aplurality of irradiation steps.
 12. The method of claim 11, wherein themethod includes agitating the granular polymeric material between atleast two irradiation steps of the plurality of irradiation steps. 13.The method of claim 7, wherein the method further includes cooling thegranular polymeric material during the irradiating.
 14. The method ofclaim 7, wherein the irradiating includes at least one of: (i)irradiating with a beam dosage of at least 20 megarads; (ii) irradiatingwith a beam dosage of at most 10⁶ megarads; and (iii) irradiating with abeam dosage selected to generate at least one desired mechanicalproperty in the crosslinked polymer granules.
 15. The method of claim 1,wherein the crosslinking includes: (i) combining the granular polymericmaterial with a crosslinking agent to form a material-agent mixture; and(ii) extruding the material-agent mixture with an extrusion apparatus toat least partially form the plurality of crosslinked polymer granules.16. The method of claim 15, wherein the extruding includes extruding toform an extruded crosslinked polymeric material, and further wherein theforming the plurality of crosslinked polymer granules includes severingthe extruded crosslinked polymeric material to form the plurality ofcrosslinked polymer granules.
 17. The method of claim 15, wherein thecrosslinking agent includes at least one of: (i) a peroxide; (ii) anorganic peroxide; (iii) di-(2,4-dichlorobenzoyl) peroxide; (iv)tert-butyl peroxybenzoate; (v)1,1-di-(tert-butylperoxy)-3,3,5-trimethylecyclohexane; (vi) dicumylperoxide; (vii) tert-butyl cumyl peroxide; (viii) di-tert-butylperoxide; (ix) 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3; (x)2,5-di(2-tert-butyl peroxyisopropyl)-benzene; (xi)2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; (xii) a silane; and (xiii)an azo compound.
 18. The method of claim 15, wherein the combiningincludes combining such that the material-agent mixture includes atleast 0.5 weight percent of the crosslinking agent.
 19. The method ofclaim 1, wherein the granular polymeric material includes polyethylenepellets generated within a polyethylene reactor.
 20. The method of claim19, wherein the method further includes generating the polyethylenepellets within the polyethylene reactor, and further wherein thegenerating includes selecting at least one property of a catalyst,utilized within the polyethylene reactor, such that a characteristicdimension of the granular polymeric material is at least 10 micrometersand at most 5 millimeters.